input.cc

// Copyright (c) 2015-2017 DMOJ: Modern Online Judge. All rights reserved.
// Copyright 2012 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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#include "v8dmoj.h"

#include <cstdio>
#include <cstdlib>
#include <cstring>

// The callback that is invoked by v8 whenever the JavaScript 'gets'
// function is called.  Returns one line from stdin.
void Gets(const v8::FunctionCallbackInfo<v8::Value> &args) {
  int bufSize = 1024, valid = 0, extra = 1024;
  char *buffer = (char *)std::malloc(1024), *str = buffer;
  if (!buffer) {
    args.GetIsolate()->ThrowException(
        v8::String::NewFromUtf8(args.GetIsolate(), "Out of memory")
            .ToLocalChecked());
    return;
  }

  buffer[0] = 0;
  while (true) {
    if (std::fgets(str, extra, stdin) == NULL) break;
    valid += std::strlen(str);
    if (buffer[valid - 1] == '\n') break;
    extra = bufSize;
    char *newBuf = (char *)std::realloc(buffer, bufSize *= 2);
    if (!newBuf) {
      args.GetIsolate()->ThrowException(
          v8::String::NewFromUtf8(args.GetIsolate(), "Out of memory")
              .ToLocalChecked());
      return;
    }
    buffer = newBuf;
    str = buffer + valid;
  }
  while (buffer[valid - 1] == '\n' || buffer[valid - 1] == '\r') --valid;
  args.GetReturnValue().Set(v8::String::NewFromUtf8(args.GetIsolate(), buffer,
                                                    v8::NewStringType::kNormal,
                                                    valid)
                                .ToLocalChecked());
  std::free(buffer);
}

void InitializeInputModule(v8::Isolate *isolate,
                           v8::Local<v8::ObjectTemplate> &global) {
  // Bind the global 'gets' function to the C++ Gets callback.
  global->Set(
      v8::String::NewFromUtf8(isolate, "gets", v8::NewStringType::kNormal)
          .ToLocalChecked(),
      v8::FunctionTemplate::New(isolate, Gets));
}